Optical amplifier

Abstract

A method of amplifying, transmitting and receiving a signal light. The method includes multiplexing the signal light and a pumping light from a pumping light source so as to output the signal light and the pumping light, and amplifying the signal light by utilizing the pumping light and providing an output of amplified signal light. The amplified signal light and the pumping light are received and the amplified signal light and the pumping light are separately outputted. The outputted amplified signal light is received and a waveform of the amplified signal light is modified so as to compensate for waveform distortion of the signal light along a transmission path of the signal light and an output of a waveform modified signal light is provided. The waveform modified signal light which is received and the pumping light which is received is multiplexed so as to output the waveform modified signal light and the pumping light. The waveform modified signal light is amplified by utilizing the pumping light and an output of amplified waveform modified signal light is outputted as the signal light output so that a reduction of optical signal level due to loss is suppressed.

What is claimed is:  
     
       1. A method of amplifying a signal light comprising the steps of: 
       multiplexing a signal light and a pumping light from a pumping light source so as to output the signal light and the pumping light;  
       amplifying the signal light by utilizing the pumping light and providing an output of amplified signal light;  
       receiving the amplified signal light and the pumping light and separately outputting the amplified signal light and the pumping light;  
       receiving the amplified signal light and modifying a waveform of the amplified signal light so as to compensate for waveform distortion of the signal light while causing a loss of signal light level by the compensation operation along a transmission path of the signal light and providing an output of a waveform modified signal light having a decreased output light level:  
       multiplexing the waveform modified signal light which is received and the pumping light which is received so as to output the waveform modified signal light and the pumping light; and  
       amplifying the waveform modified signal light by utilizing the pumping light and providing an output of amplified waveform modified signal light as the signal light output;  
       wherein a reduction of optical signal level due to the loss caused by compensation for the waveform distortion of the signal light is suppressed; and  
       wherein the signal light includes light at plural wavelengths and the step of modifying the waveform of the amplified signal light includes utilizing a wavelength dependent equalizing filter and providing the output of the waveform modified signal light which is a wavelength equalized.  
     
     
       2. A method of amplifying a signal light comprising the steps of: 
       multiplexing a signal light and a pumping light from a pumping light source so as to output the signal light and the pumping light;  
       amplifying the signal light by utilizing the pumping light and providing an output of amplified signal light;  
       receiving the amplified signal light and the pumping light and separately outputting the amplified signal light and the pumping light;  
       receiving the amplified signal light and modifying a waveform of the amplified signal light so as to compensate for waveform distortion of the signal light while causing a loss of signal light level by the compensation operation along a transmission path of the signal light and providing an output of a waveform modified signal light having a decreased output light level;  
       multiplexing the waveform modified signal light which is received and the pumping light which is received so as to output the waveform modified signal light and the pumping light; and  
       amplifying the waveform modified signal light by utilizing the pumping light and providing an output of amplified waveform modified signal light as the signal light output;  
       wherein a reduction of optical signal level due to the loss caused by compensation for the waveform distortion of the signal light is suppressed; and  
       wherein the signal light includes light at plural wavelengths, and modifying the waveform of the amplified signal light includes utilizing a dispersion compensation fiber and a wavelength dependent equalizing filter coupled to the dispersion compensation fiber and providing an output of the waveform modified signal light which is wavelength equalized.  
     
     
       3. A method of amplifying a signal light comprising the steps of: 
       multiplexing a signal light and a pumping light from a pumping light source so as to output the signal light and the pumping light;  
       amplifying the signal light by utilizing the pumping light and providing an output of amplified signal light;  
       receiving the amplified signal light and the pumping light and separately outputting the amplified signal light and the pumping light;  
       compensating for distortion of the signal light including receiving the amplified signal light and modifying a waveform of the amplified signal light so as to compensate for waveform distortion of the signal light while causing a loss of signal light level by the compensation operation along a transmission path of the signal light and providing an output of a waveform modified signal light having a decreased output light level;  
       multiplexing the waveform modified signal light which is received and the pumping light which is received so as to output the waveform modified signal light and the pumping light; and  
       amplifying the waveform modified signal light by utilizing the pumping light and providing an output of amplified waveform modified signal light as the signal light output;  
       wherein a reduction of optical signal level due to the loss caused by compensation for the waveform distortion of the signal light is suppressed; and  
       wherein the signal light includes light at plural wavelengths and the step of compensating for distortion of the signal light includes utilizing a wavelength dependent equalizing filter and providing the output of the waveform modified signal light which is wavelength equalized.